The technology relates to scalable testing of complex networks and/or complex network devices. Network test equipment to perform such useful scalable testing should emulate a large number and variety of network devices without artificial limits on the overall topology, configuration, and types of traffic.
Traffic types vary by supported network layer, link layer, and physical layer protocols, such as Internet Protocol, Generic Routing Encapsulation, Ethernet, Virtual Local Area Network 802.1q, Multiprotocol Label Switching, Point to Point Protocol over Ethernet, Point to Point Protocol, and Layer 2 Tunneling Protocol, WiMAX, Provider Backbone Bridge 802.1ah, and Asynchronous Transfer Mode. Existing network test equipment places artificial limits on the types of emulated traffic, in particular variable combinations of network layer, link layer, and physical layer protocols.
One prior approach to handling MPLS packets does not perform transmit forward equivalence class classification, but rather is a shortcut which falls well short of transmit forward equivalence class classification. This shortcut combines a forward equivalence class that is static, with dynamic binding of only the MPLS label. This shortcut does not perform forward equivalence class classification on packets, for multiple reasons. Because the shortcut determines the static forward equivalence class information before the packets even exist, the shortcut is not performing forward equivalence class classification; transmit forward equivalence class classification requires that the packets exist prior to performing forward equivalence class classification, and that the packet contents be analyzed to determine an IP address of a next hop router and an IP address of a resolving router. Instead, this short cut requires that a human user manually specify FEC binding information, in particular the IP address of a next hop router, and the IP address of a resolving router. This requirement of manual entry by a human user is driven by the following consideration. When multiple transmit FEC classifications are required to transmit a packet, the result of a subsequent FEC classification depends on the result of a prior FEC classification, and thus may be performed correctly only with a correct method. Accordingly, because this shortcut depends on FEC-to-label bindings at a particular time, which may be changing, manual entry by a human user is required. Dynamically assigning a label value to packets still does not perform forward equivalence class classification on packets. The fact that different labels are assigned does not change the static nature of the FEC to which it has been mapped.
Another prior approach to handling MPLS packets does not perform receive forward equivalence class classification, but rather is a shortcut which falls well short of receive forward equivalence class classification. This prior approach simply throws away the MPLS label, without accessing the forward equivalence class binding, and without determining the forward equivalence class and next layer protocol from the binding. Instead, this prior approach guesses the next layer protocol without use of the forward equivalence class binding. The prior approach assumes a valid FEC binding which may not even exist.